參考原文

• 一案训、適配Dark Mode

  顏色適配
  圖片適配

• 二斤程、獲取當(dāng)前模式(Light or Dark)

• 三、其他內(nèi)容

• 四专筷、總結(jié)

一、適配Dark Mode

1 顏色適配

• iOS13 之前 UIColor只能表示一種顏色蒸苇，而從 iOS13 開始UIColor是一個(gè)動(dòng)態(tài)的顏色磷蛹，在Light Mode和Dark Mode可以分別設(shè)置不同的顏色。
• iOS13系統(tǒng)提供了一些動(dòng)態(tài)顏色

) UIColor *systemBrownColor        API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *systemIndigoColor       API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *systemGray2Color        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *systemGray3Color        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *systemGray4Color        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *systemGray5Color        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *systemGray6Color        API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *labelColor              API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *secondaryLabelColor     API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *tertiaryLabelColor      API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *quaternaryLabelColor    API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *linkColor               API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *placeholderTextColor    API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *separatorColor          API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *opaqueSeparatorColor    API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
@property (class, nonatomic, readonly) UIColor *systemBackgroundColor                   API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *secondarySystemBackgroundColor          API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *tertiarySystemBackgroundColor           API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *systemGroupedBackgroundColor            API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *secondarySystemGroupedBackgroundColor   API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *tertiarySystemGroupedBackgroundColor    API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *systemFillColor                         API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *secondarySystemFillColor                API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *tertiarySystemFillColor                 API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);
@property (class, nonatomic, readonly) UIColor *quaternarySystemFillColor               API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos, watchos);

① 實(shí)例

[self.view setBackgroundColor:[UIColor systemBackgroundColor]];
[self.titleLabel setTextColor:[UIColor labelColor]];
[self.detailLabel setTextColor:[UIColor placeholderTextColor]];

系統(tǒng)UIColor樣式
用法和iOS13之前的一樣溪烤，使用系統(tǒng)提供的這些動(dòng)態(tài)顏色味咳，不需要其他的適配操作

② 自定義動(dòng)態(tài)UIColor

在實(shí)際開發(fā)過程，系統(tǒng)提供的這些顏色還遠(yuǎn)遠(yuǎn)不夠檬嘀，因此我們需要?jiǎng)?chuàng)建更多的動(dòng)態(tài)顏色
初始化動(dòng)態(tài)UIColor方法
iOS13 UIColor增加了兩個(gè)初始化方法槽驶，使用以下方法可以創(chuàng)建動(dòng)態(tài)UIColor
注:一個(gè)是類方法，一個(gè)是實(shí)例方法

+ (UIColor *)colorWithDynamicProvider:(UIColor * (^)(UITraitCollection *))dynamicProvider API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);
- (UIColor *)initWithDynamicProvider:(UIColor * (^)(UITraitCollection *))dynamicProvider API_AVAILABLE(ios(13.0), tvos(13.0)) API_UNAVAILABLE(watchos);

這兩個(gè)方法要求傳一個(gè)block進(jìn)去
當(dāng)系統(tǒng)在LightMode和DarkMode之間相互切換時(shí)就會(huì)觸發(fā)此回調(diào)
這個(gè)block會(huì)返回一個(gè)UITraitCollection類
我們需要使用其屬性userInterfaceStyle鸳兽，它是一個(gè)枚舉類型掂铐，會(huì)告訴我們當(dāng)前是LightMode還是DarkMode

typedef NS_ENUM(NSInteger, UIUserInterfaceStyle) {
    UIUserInterfaceStyleUnspecified,
    UIUserInterfaceStyleLight,
    UIUserInterfaceStyleDark,
} API_AVAILABLE(tvos(10.0)) API_AVAILABLE(ios(12.0)) API_UNAVAILABLE(watchos);

實(shí)例

UIColor *dyColor = [UIColor colorWithDynamicProvider:^UIColor * _Nonnull(UITraitCollection * _Nonnull trainCollection) {
        if ([trainCollection userInterfaceStyle] == UIUserInterfaceStyleLight) {
            return [UIColor redColor];
        }
        else {
            return [UIColor greenColor];
        }
    }];
    
 [self.bgView setBackgroundColor:dyColor];

2.圖片適配

• 打開Assets.xcassets
• 新建一個(gè)Image set
• 打開右側(cè)工具欄，點(diǎn)擊最后一欄揍异，找到Appearances全陨，選擇Any，Dark
• 將兩種模式下不同的圖片資源都拖進(jìn)去
• 使用該圖片

3.獲取當(dāng)前模式(Light or Dark)

有時(shí)候我們需要知道當(dāng)前處于什么模式蒿秦，并根據(jù)不同的模式執(zhí)行不同的操作
iOS13中CGColor依然只能表示單一的顏色
通過調(diào)用UITraitCollection.currentTraitCollection.userInterfaceStyle
獲取當(dāng)前模式

實(shí)例

if (UITraitCollection.currentTraitCollection.userInterfaceStyle == UIUserInterfaceStyleDark) {
        [self.titleLabel setText:@"DarkMode"];
    }
    else {
        [self.titleLabel setText:@"LightMode"];
    }
}

其他

1.監(jiān)聽模式切換

有時(shí)我們需要監(jiān)聽系統(tǒng)模式的變化烤镐，并作出響應(yīng)
那么我們就需要在需要監(jiān)聽的viewController中蛋济，重寫下列函數(shù)

// 注意:參數(shù)為變化前的traitCollection
- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection;
 
// 判斷兩個(gè)UITraitCollection對象是否不同
- (BOOL)hasDifferentColorAppearanceComparedToTraitCollection:(UITraitCollection *)traitCollection;

① 示例

- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection {
    [super traitCollectionDidChange:previousTraitCollection];
    // trait發(fā)生了改變
    if ([self.traitCollection hasDifferentColorAppearanceComparedToTraitCollection:previousTraitCollection]) {
    // 執(zhí)行操作
    }
    }

2.CGColor適配

我們知道iOS13后棍鳖，UIColor能夠表示動(dòng)態(tài)顏色，但是CGColor依然只能表示一種顏色碗旅，那么對于CALayer等對象如何適配暗黑模式呢?當(dāng)然是利用上一節(jié)提到的監(jiān)聽模式切換的方法啦渡处。

- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection {
    [super traitCollectionDidChange:previousTraitCollection];
    UIColor *dyColor = [UIColor colorWithDynamicProvider:^UIColor * _Nonnull(UITraitCollection * _Nonnull trainCollection) {
        if ([trainCollection userInterfaceStyle] == UIUserInterfaceStyleLight) {
            return [UIColor redColor];
        }
        else {
            return [UIColor greenColor];
        }
    }];
        layer.backgroundColor = dyColor.CGColor;
}

??!!! 設(shè)置layer顏色都是在traitCollectionDidChange中，意味著如果沒有發(fā)生模式切換祟辟，layer將會(huì)沒有顏色医瘫，需要設(shè)置一個(gè)基本顏色

3.模式切換時(shí)打印log

模式切換時(shí)自動(dòng)打印log，就不需要我們一次又一次的執(zhí)行po命令了

• 在Xcode菜單欄Product->Scheme->Edit Scheme
• 選擇Run->Arguments->Arguments Passed On Launch
• 添加以下命令即可
  -UITraitCollectionChangeLoggingEnabled YES

4.強(qiáng)行設(shè)置App模式

當(dāng)系統(tǒng)設(shè)置為Light Mode時(shí)旧困，對某些App的個(gè)別頁面希望一直顯示Dark Mode下的樣式醇份，這個(gè)時(shí)候就需要強(qiáng)行設(shè)置當(dāng)前ViewController的模式了

// 設(shè)置當(dāng)前view或viewCongtroller的模式
@property(nonatomic) UIUserInterfaceStyle overrideUserInterfaceStyle;

示例

// 設(shè)置為Dark Mode即可
[self setOverrideUserInterfaceStyle:UIUserInterfaceStyleDark];

?? 注意!!!

當(dāng)我們強(qiáng)行設(shè)置當(dāng)前viewController為Dark Mode后稼锅，這個(gè)viewController下的view都是Dark Mode
由這個(gè)ViewController present出的ViewController不會(huì)受到影響，依然跟隨系統(tǒng)的模式
要想一鍵設(shè)置App下所有的ViewController都是Dark Mode僚纷，請直接在Window上執(zhí)行overrideUserInterfaceStyle
對window.rootViewController強(qiáng)行設(shè)置Dark Mode也不會(huì)影響后續(xù)present出的ViewController的模式

5.NSAttributedString優(yōu)化

對于UILabel矩距、UITextField、UITextView怖竭，在設(shè)置NSAttributedString時(shí)也要考慮適配Dark Mode锥债，否則在切換模式時(shí)會(huì)與背景色融合，造成不好的體驗(yàn)

不建議的做法

NSDictionary *dic = @{NSFontAttributeName:[UIFont systemFontOfSize:16]};
NSAttributedString *str = [[NSAttributedString alloc] initWithString:@"富文本文案" attributes:dic];

推薦的做法

// 添加一個(gè)NSForegroundColorAttributeName屬性
NSDictionary *dic = @{NSFontAttributeName:[UIFont systemFontOfSize:16],NSForegroundColorAttributeName:[UIColor labelColor]};
NSAttributedString *str = [[NSAttributedString alloc] initWithString:@"富文本文案" attributes:dic]

總結(jié)

總的來說痊臭，iOS13主要有以下變化:
1.支持 Dark Mode
2.UIColor變?yōu)閯?dòng)態(tài)顏色
3.更新StatusBar樣式
4.更新UIActivityIndicatorView樣式